This invention relates to sheeting which is electrically conductive on one surface and antistatic on the opposite surface. Such sheeting is especially suited to use in environments where accumulation of static electricity on the surface of the sheeting material would be hazardous.
Various coated or laminated fabrics having electrically conductive films bonded to the exterior surface of a base fabric, e.g. a cotton fabric are available. However, in view of the poor adhesion of the coating to the base woven fabric, the conductive coating tends to abrade, crock or crack and thus tends to become separated from the fabric. Therefore, it is difficult in such laminates to provide an integral material with a substantial useful lifetime.
In my U.S. Pat. No. 3,891,786, which is assigned to the assignee of the present application, an electrically conductive sheeting is described whereby a rubber composition containing about 25 to about 40% by weight of an electrical grade carbon black is coated onto a plastic layer. Before or after application of this coating, the plastic layer is perforated. The perforations may be sealed thereafter by a suitable heat-sealing with heated rollers or the like. Conductive properties are thus provided on the surface of the fabric.
References cited during the prosecution of U.S. Pat. No. 3,891,786 provide a background of the prior art in this area. Thus, U.S. Pat. No. 3,783,085 describes laminated articles which may comprise fabric layers containing a core of activated charcoal particles and a powdered thermoplastic adhesive. The function of the activated charcoal component is to absorb toxic vapors as contaminated air passes through the air-permeable substrates of the fabric.